Biomedical Engineering Reference
In-Depth Information
Fig. 10 Confocal laser scanning microscope images of islets with urokinase (UK) immobilized on
the membrane. The
green fluorescence
indicates positive immunostaining for UK. (a) Islets were
modified with oligo(dT)
20
-PEG-lipid (C16) or (b) oligo(dT)
20
-PEG-lipid (C18); then, oligo
(dA)
20
-UK was added to the media. (c) Unmodified islets with (
left
) and without (
right
) oligo
(dT)
20
-PEG-lipids added to the solution.
Insets
: Bright field images. Scale bars: 100
m
m
function of the UK attached to the islets. Fifty islets with or without immobilization
of UK were spotted onto a fibrin gel plate. After incubation, transparent areas
around the spots indicated UK dissolution of the fibrin. Figure
11
shows the fibrin
plate at 14 h after spotting the islets. Larger transparent areas were observed around
the UK-islets compared to those around the unmodified islets (Fig.
11a
-1, a-2, a-4).
These indicated that the immobilized UK retained its activity on the islets.
UK-islets were also tested after 2 days of culture in the presence of serum
(Fig.
11a
-3, a-5). UK activity rapidly decreased with 2 days in culture. The
morphology of all islets after modification with UK was well maintained after
7 days of culture (Fig.
11b
). Islets with UK maintained the ability to regulate insulin
release in response to changes in glucose concentration (data not shown). We also
performed transplantation of UK-islets by transfusion to the liver through the portal
vein [
119
]. The transplantation results indicated that donor islets were rescued from
host defenses by attaching UK to their surfaces. It remains to be determined how
